你好，我有一个QR码图像，我想调整它，当我尝试使用此代码把它调整到一个小图像，我总是得到一个blury图像和QR码不再有效时，我扫描了，但当我调整到具有相同的代码一个大尺寸的图像，它工作正常：
public BufferedImage getScaledInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality)
{
int type = (img.getTransparency() == Transparency.OPAQUE) ?
BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage)img;
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w > targetWidth) {
w /= 2;
if (w < targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h > targetHeight) {
h /= 2;
if (h < targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(w, h, type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
// g2.setRenderingHint(RenderingHints.KEY_DITHERING, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
} while (w != targetWidth || h != targetHeight);
return ret;
}
是什么问题，我完全不明白，请给我至少一个提示，谢谢
Answer 1:
我用仿射变换来实现这一任务，这里是我的代码，希望它有助于
/**
* scale image
*
* @param sbi image to scale
* @param imageType type of image
* @param dWidth width of destination image
* @param dHeight height of destination image
* @param fWidth x-factor for transformation / scaling
* @param fHeight y-factor for transformation / scaling
* @return scaled image
*/
public static BufferedImage scale(BufferedImage sbi, int imageType, int dWidth, int dHeight, double fWidth, double fHeight) {
BufferedImage dbi = null;
if(sbi != null) {
dbi = new BufferedImage(dWidth, dHeight, imageType);
Graphics2D g = dbi.createGraphics();
AffineTransform at = AffineTransform.getScaleInstance(fWidth, fHeight);
g.drawRenderedImage(sbi, at);
}
return dbi;
}
Answer 2:
我写了这个类，我个人也使用。 我希望的代码是直线前进。
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.awt.image.CropImageFilter;
import java.awt.image.FilteredImageSource;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
public class ImageScaler {
private ImageIcon originalImage;
private ImageIcon scaledImage;
public ImageScaler(Image image) {
this.originalImage = new ImageIcon(image);
}
public ImageScaler(String fileName) {
originalImage = new ImageIcon(fileName);
}
public void createScaledImage(int size, ScalingDirection scalingDirection) {
if (scalingDirection == ScalingDirection.HORIZONTAL) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(size, -1, Image.SCALE_SMOOTH));
} else {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(-1, size, Image.SCALE_SMOOTH));
}
}
public void createScaledImage(int size, ScalingDirection scalingDirection, int scale) {
if (scalingDirection == ScalingDirection.HORIZONTAL) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(size, -1, scale));
} else {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(-1, size, scale));
}
}
public void createScaledImage(int width, int height, ScaleType scaleType) {
int imageWidth = originalImage.getImage().getWidth(null);
int imageHeight = originalImage.getImage().getHeight(null);
double originalImageRatio = imageWidth / (double) imageHeight;
double scaledImageRatio = width / (double) height;
if(scaleType == ScaleType.FIT) {
if(imageHeight - (Math.abs(imageWidth - width) / originalImageRatio) <= height) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(width, -1, Image.SCALE_SMOOTH));
} else if(imageWidth - (Math.abs(imageHeight - height) * originalImageRatio) <= width) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(-1, height, Image.SCALE_SMOOTH));
}
} else if(scaleType == ScaleType.FILL) {
if(imageHeight - (Math.abs(imageWidth - width) / originalImageRatio) >= height) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(width, -1, Image.SCALE_SMOOTH));
int thumbHeight = scaledImage.getImage().getHeight(null);
// Crop the image
scaledImage = new ImageIcon(Toolkit.getDefaultToolkit().createImage(new FilteredImageSource(scaledImage.getImage().getSource(), new CropImageFilter(0, (thumbHeight-height)/2, width, height))));
} else if(imageWidth - (Math.abs(imageHeight - height) * originalImageRatio) >= width) {
scaledImage = new ImageIcon(originalImage.getImage().getScaledInstance(-1, height, Image.SCALE_SMOOTH));
int thumbWidth = scaledImage.getImage().getWidth(null);
// Crop the image
scaledImage = new ImageIcon(Toolkit.getDefaultToolkit().createImage(new FilteredImageSource(scaledImage.getImage().getSource(), new CropImageFilter((thumbWidth-width)/2, 0, width, height))));
}
}
}
public void saveScaledImage(File file, ImageType imageType) {
if (scaledImage != null) {
BufferedImage bi = new BufferedImage(scaledImage.getIconWidth(), scaledImage.getIconHeight(), BufferedImage.TYPE_INT_RGB);
Graphics g = bi.getGraphics();
g.drawImage(scaledImage.getImage(), 0, 0, null);
try {
ImageIO.write(bi, imageType.value(), file);
} catch (IOException ioe) {
System.out.println("Error occured saving scaled image");
}
} else {
System.out.println("Scaled image has not yet been created");
}
}
public void saveOriginalImage(File file, ImageType imageType) {
if (originalImage != null) {
BufferedImage bi = new BufferedImage(originalImage.getIconWidth(), originalImage.getIconHeight(), BufferedImage.TYPE_INT_RGB);
Graphics g = bi.getGraphics();
g.drawImage(originalImage.getImage(), 0, 0, null);
try {
ImageIO.write(bi, imageType.value(), file);
} catch (IOException ioe) {
System.out.println("Error occured saving original image");
}
} else {
System.out.println("Original image has not yet been created");
}
}
// ENUMS
public enum ScalingDirection {VERTICAL, HORIZONTAL};
public enum ScaleType {FIT, FILL};
public enum ImageType {
IMAGE_JPEG ("jpeg"),
IMAGE_JPG ("jpg"),
IMAGE_PNG ("png");
private String value = null;
ImageType(String value) {
this.value = value;
}
String value() {
return value;
}
};
}
Answer 3:
根据@ A4L的回答：
更straigt前的版本。 此外他的解决办法也只能扩展画布不是图像本身。
public static BufferedImage scale(BufferedImage imageToScale, int dWidth, int dHeight) {
BufferedImage scaledImage = null;
if (imageToScale != null) {
scaledImage = new BufferedImage(dWidth, dHeight, imageToScale.getType());
Graphics2D graphics2D = scaledImage.createGraphics();
graphics2D.drawImage(imageToScale, 0, 0, dWidth, dHeight, null);
graphics2D.dispose();
}
return scaledImage;
}
以提高质量，你可以添加
graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
graphics2D.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
Answer 4:
请看看这个Image.getScaledInstance（）细节可以在这个答案中找到： 如何提高g.drawImage的），用于调整图像大小的性能（方法
希望能帮助到你
Answer 5:
public static BufferedImage resizeImg(BufferedImage img, int newW, int newH)
{
int w = img.getWidth();
int h = img.getHeight();
BufferedImage dimg = new BufferedImage(newW, newH, img.getType());
Graphics2D g = dimg.createGraphics();
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(img, 0, 0, newW, newH, 0, 0, w, h, null);
g.dispose();
return dimg;
}
Answer 6:
我建议Thumbnailnator ，因为它给了我更好的图像质量比Java多步骤方法。 然而，速度也可能会与你的Graphics2D的drawImage代码更好。
又见爪哇-调整图像不失品位
Answer 7:
其实，解决的办法是更简单。 您不必创建一个新的BufferedImage。 您可以应用for3st提到直接以原BufferedImage的图像（“图像”）的方法，并设置宽度和高度，你想它。 因此，只需要一个单一的声明（包括stadard Java文档）：
drawImage(BufferedImage image, int x, int y, int width, int height, ImageObserver observer)
文章来源: how to resize Image in java?
